So, through a bit of research, I found that the base level G6 (same platform) came with 4 wheel disc non ABS. I then went to ACDelco's website and found that there was a different part number for the proportioning valve on said G6 (ACD# 15821482) and in the picture, the outward appearance was just like mine. So I'm thinking the internals are different and it will bolt right in. PERFECT!!! Except, the part has been discontinued. Called all the local salvage yards and looked all over the interwebs for a needle in a haystack. Put a request in on junkyarddog.com and got a response the next day. After a conversation on the phone, I paid more than expected, got the part shipped in a few days, installed everything and drove it home that night. It stops a lot better now. Lol.